- Problem Description
DP extended display: When hot-plugging the downstream DP port, there is no audio output. (Occurs randomly) 2. Setup Condition The product is connected to the following platform: Platform: Apple MacBook Pro (16-inch, M4 Max, 2024) The DP port is connected to the following monitor: 3. Reproduction Procedure Step 1: Connect the DP port to the extended display ASUS VP28U (4K 60Hz) Step 2: Connect the platform Apple MacBook Pro (16-inch, M4 Max, 2024) Step 3: Hot-plug the downstream DP port → no audio output (random occurrence) Bug Description DP extended display: When hot-plugging the downstream DP port, there is no audio output. (Random) Affected Platform & Monitor Combination Apple MacBook Pro (16-inch, M4 Max, 2024) & Samsung S32BG850NC (4K 240Hz) Vendor Anaysis: After analysis, we found that the issue also fails when the host is directly connected to the monitor (tested with two different USB-C to DP cables, both showing the same failure). The RTS5490 only bypasses the audio and video signals, and no abnormal behavior was observed in the logs. In addition, we found that different behaviors occur when switching the monitor OSD between DP 1.1 and DP 1.2: OSD set to DP 1.1: Direct connection: Pass Connected through RTS5490: Pass OSD set to DP 1.2: Direct connection: Fail Connected through RTS5490: Fail (same issue reported by Tongxing) Testing with other monitors does no